Farm operators have moved away from conventional tillage of field surfaces prior to seeding to doing minimal or no tillage at all prior to seeding. In dry conditions these no-till operations have increased yields by preserving moisture to be used by growing crops, however in wet conditions significant problems arise.
When fields are wet at harvest time combines and grain moving wagons sink into the surface creating severe ruts. Wet harvests often also result in crops not being harvested at all before winter, such that in the spring the crop is ruined and lying on the field surface causing significant difficulties with the operation of equipment to seed the next crop.
Primary tillage using implements that penetrate relatively deeply into the soil surface is often used to address these problems. Tillage using heavy disc implements with highly concave discs set at an angle to the operating travel direction is often used to bury the crop lying on the field surface. Tillage using cultivators with shovels on the bottom of shanks, and commonly with harrows behind, can bury and spread the crop or crop residue lying on the field surface. Such primary tillage also smooths ruts left in the field.
When fields are wet at seeding time secondary tillage using implements that penetrate relatively shallowly into the soil surface is often used to disturb the soil surface and expose the soil so same will dry. Such secondary tillage also smooths most ruts left in the field and spreads and buries crop residue to facilitate seeding operations.
“Vertical” tillage appears to have no accepted definition but is also becoming common. In vertical tillage implements flat or slightly concave discs are oriented parallel to the operating travel direction or at a slight angle thereto. The discs penetrate the ground to form a slot in the slot surface and break up crop residue and disturb the soil.
Typically the main tillage tools used in primary and secondary tillage implements include a variety of discs and a variety of shovels mounted on the bottom end of cultivator shanks.
The discs can be concave or flat and may include notches on the circumference thereof. The discs are oriented anywhere from aligned with the operating travel direction to an angle of 20 degrees or more from the operating travel direction. In some implements a plurality of discs are mounted on a common shaft to form a gang and the gangs are mounted side by side across the width of the implement. In other implements the discs are mounted individually to the frame with a trip system such that each disc can move up and down independently.
The shovels mounted on the bottom end of cultivator shanks vary in width from narrow spikes which may be only an inch wide to sweeps that are wide enough to turn over all the soil that the implement passes over. Many of these main tillage tools such as concave discs and shovels are configured such that once engaged in the soil surface they tend to at least somewhat draw themselves into the soil.
Discs and shovels generally leave the soil loose and ridged. To provide a desirable smooth and packed seed bed behind the discs or shovels, harrows or rolling baskets or both are often mounted to the implement frame rearward of the main tillage tools.
The John Deere™ 2310 Mulch Finisher made by Deere & Co. of Moline, Ill., USA includes a row of slightly concave discs in gangs mounted along a front of the implement, followed by an array of cultivator shanks, with harrows behind the shanks and rolling baskets available behind the harrows to smooth the soil surface. The shanks are mounted to the frame with spring trip assemblies with a 200 pound trip force. This implement is only useful for lighter secondary tillage since the 200 pound trip force is not sufficient to keep the shank mounted tools in the fully lowered and engaged position at deeper penetration depths required for primary tillage.
Great Plains Manufacturing of Salina, Kans., USA makes a very similar implement in their 8000 Series Disc-o-vator. The 8000 Series implement also includes a row of similar disc gangs followed by an array of cultivator shanks, with harrows behind the shanks and rolling baskets behind the harrows. Again the shanks are mounted to the frame with light spring trip assemblies and this implement is also only useful for lighter secondary tillage.